This was the week the big one finally came clean in the DIRT inquiry. The long-awaited settlement between AIB Group and the Revenue Commissioners was concluded and announced.

All in all, it was a bit of a damp squib. So much so that Committee of Public Accounts (PAC) chairman Jim Mitchell was moved to issue a statement from his hospital bed expressing his disappointment.

You can see why. Every settlement to date has been a multiple of the exposure estimated by the institutions themselves. Not AIB. The greatest offender in the non-resident account scam ended up paying less than it had initially forecast itself - and that includes interest and penalties. Mind you, it still topped £90 million.

So why so low and, if so low, why such a knock-it-down, drag-it-out battle to extract the money owed?

AIB continues to insist it had a deal with the Revenue but that it decided in the end that the public wanted it to pay up and that it would be easier to do so.

That doesn't quite wash. If it had a deal, it would be most unlike AIB to opt against taking the issue to court, as it had threatened earlier to do so. And as for listening to the public; if AIB had been doing that, it would have paid up when the story broke and saved itself the embarrassment of a roasting by the PAC.

As to why the figure was so low, the conspiracy theorists are still looking for the story behind the story. Could it be simply that AIB is that much better at working out its sums than its rivals?